Known slide gates are provide at the pouring hole of liquid metal containers, in particular tundishes and ladles. They comprise a base plate rigid with the base plate and a movable plate kept adhering to the fixed plate in a manner movable tangentially thereto. Both the plates comprise a hole which when the plates face each other are aligned to allow the pouring jet to pass, and which when the position of the movable plate is varied relative to the fixed plate intercept this jet.
Slide gates in the form of three superposed plates are also known, of which the two outer plates are fixed and are each provided with a hole coaxial to that of the other plate, whereas the intermediate plate, also provided with a hole, is movable longitudinally between the two fixed plates to align its hole with the holes in these, and achieve a continuous passage for the molten metal towards the underlying casting trough.
These slide gates are generally provided with coupling systems for the two/three plates, consisting of a support structure housing springs which act in the sense of pressing the lower plate against the upper plate to ensure sealed contact, and a plurality of locking members and levers which retain the plates together and enable the slide gate to be opened and closed.
As the opening/closure of the gate structure and the replacement of the worn refractories are done manually, these known slide gates have certain drawbacks, and in particular:
they require prolonged down-time for opening/closing the gate structure and replacing worn refractories,
they require considerable physical force from the operator operating the opening and closure levers,
they create an uncomfortable environment for the operator, who is exposed for a long time to the heat generated during the opening of the ladle/tundish when removing worn refractories.
In addition the need to open/close the gate structure manually means that from the plant design aspect the slide gate has to be installed in such a manner as to be able to be opened with the least possible force by the operator. This results in installation difficulty and additional costs for the devices required for its operation.